1. Field of the Invention
The present invention relates in general to a control apparatus for a hybrid vehicle power transmitting system, and more particularly to techniques for reducing a risk of an excessive rise of operating speeds of electric motors and a clutch provided in the power transmitting system.
2. Discussion of Prior Art
There is known a control apparatus for a power transmitting system of a hybrid vehicle provided with an engine, an electric generator and a vehicle drive electric motor, which control apparatus is arranged to reduce a torque of the engine for reducing a risk of an excessive rise of the operating speed of the vehicle drive electric motor, when the operating speed of the vehicle drive electric motor exceeds a threshold value due to slipping of drive wheels of the hybrid vehicle. JP-2003-193878A discloses an example of such a hybrid vehicle control apparatus. The hybrid vehicle control apparatus disclosed in this publication limits the operating speed of the vehicle drive electric motor, for reducing an adverse influence of the excessive rise of the operating speed of the vehicle drive electric motor on the durability of the hybrid vehicle power transmitting system.
The above-identified publication does not refer to a transmission which constitutes a part of the power transmitting system and which is arranged to switch a power transmitting path between a power transmitting state and a power cut-off state. Hence, the control apparatus disclosed in the publication is not configured to suitably control a switching portion of the power transmitting system provided to switch the power transmitting path between the power transmitting state and the power cut-off state, for reducing the risk of the excessive rise of the operating speed of the vehicle drive electric motor.